nice for pthreads? (Linux)

With Linux kernel 2.6
nice() called inside a pthread
affects only the calling thread
or all threads of the process??
(I guess in POSIX it affects the process, but Linux is not fully POSIX compliant cause threads are actually processes for the kernel scheduler)

In case it affects all process's threads, is there a call something like pthread_nice() to affect one thread only?
Please do not answer set_sched_param() cause that will not work for SCHED_OTHER policy as stated here

"pthread_setschedparam sets the scheduling parameters for the thread target_thread as indicated by policy and param. policy can be either SCHED_OTHER (regular, non-realtime scheduling), SCHED_RR (realtime, round-robin) or SCHED_FIFO (realtime, first-in first-out). param specifies the scheduling priority for the two realtime policies. See sched_setpolicy(2) for more information on scheduling policies. "
at http://www.linuxmanpages.com/man3/pt...param.3thr.php

The verbiage is unclear, but a man page isn't an official document anyway. Some Googling reveals lots of examples on the web of using pthread_setschedparam() to set the priority of a SCHED_OTHER thread -- either these examples are all wrong, or it works.

Ideally, your MT design wouldn't rely on on the scheduling algorithm, for efficiency or correctness.

Why do you feel the need to call something like "pthread_nice()"?

gg

Quote:

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Originally Posted by brewbuck

The verbiage is unclear, but a man page isn't an official document anyway. Some Googling reveals lots of examples on the web of using pthread_setschedparam() to set the priority of a SCHED_OTHER thread -- either these examples are all wrong, or it works.

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this is very curious and interesting
if you still have some links please give them!!

Quote:

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Originally Posted by Codeplug

Ideally, your MT design wouldn't rely on on the scheduling algorithm, for efficiency or correctness.

Why do you feel the need to call something like "pthread_nice()"?

gg

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I agree with you. Relying on nice is not the case, also because nice lvel is +-5 changed by the sched. But I think it helps effciency.

>> I think it helps effciency
Keep in mind that doing something faster doesn't make it more efficient :)

I look at it as "Taking cpu time away from other tasks". There's not a whole lot of good reasons for doing this.

If you can make the code "correct" regardless of scheduling, then I would do that first. In the meantime, the best I can help is to point you to the official POSIX documentation on the subject.

2.8.4 Process Scheduling - http://www.opengroup.org/onlinepubs/...l#tag_02_08_04
pthread_[g|s]etschedparam - http://www.opengroup.org/onlinepubs/...chedparam.html
pthread_setschedprio - http://www.opengroup.org/onlinepubs/...schedprio.html

gg